Tricyclo-decene tetracarboxylic acid diimide polymers

ABSTRACT

PROCESS FOR THE PRODUCTION OF POLYIMIDE POLYMERS HAVING A MOLECULAR WEIGHT LESS THAN 10**8 UNITS OBTAINED BY THE PRESENCE OF ALKALI AND OF AN AZO DYE OF THE FORMULA R-R&#39;&#39; WHEREIN   R IS   -C6H4-N=N-CH(-CO-R1)-CO-NH-R2   R&#39;&#39; IS R, HYDROGEN, LOWER ALKYL, PHENYL, DI-LOWER-ALKYLAMINE, LOWER ALKOXY, LOWER ACYLAMINE; R1 IS ALKYLC1-17 OR PHENYL; AND R2 IS ARYL, ALKYLC1-18, ALKOXY-PHENYL. PYPROPOLYMERIZATION OF TRICYCLO(4.2.20**2.5)-9-R-DEC-9-ENE3,4,7,8 TETRACARBOXYLIC ACID DIANHYDRIDE IN WHICH R IS AN ALKYL GROUP HAVING FROM 7 TO 20 CARBON ATOMS AND A C2-C12 POLYMETHYLENE DIAMINE.

United States Patent O Int. Cl. C08g 20/32 US. Cl. 260-78 TF 3 Claims ABSTRACT OF THE DISCLOSURE Process for the production of polyimide polymers having a molecular weight less than 10 units obtained by the pyropolymerization of tricyc1o[4.2.2.O ]-9-R-dec-9-ene- 3,4,7,8 tetracarboxylic acid dianhydride in which R is an alkyl group having from 7 to 20 carbon atoms and a C -C polymethylene diamine.

CROSS REFERENCES This application is a divisional of copending application Ser. No. 495,345, filed Oct. 12, 1965, now US. Patent No. 3,413,316. r

This invention relates to an improved process for the formation of benzene-maleic anhydride adducts.

It is known that maleic anhydride reacts with benzene or mono-substituted benzenes under the influence of actinic light. It is also known that added aryl ketones make an otherwise impracticable reaction appreciably better in terms of rate and conversions. On the other hand, the reaction suffers from substantial disadvantages despite the presence of the added ketone. Among these is the strong adherence of the odorous aryl ketones to the desired adduct and of the equally odorous photoinduced aryl ketone fragmentation products. Another is the consumption of costly aromatic ketones in the process.

It has now been found that an actinic light induced reaction of maleic anhydride with benzene hydrocarbons of the formula C5H5R in which R is hydrogen or a saturated hydrocarbon radical having fewer than about 21 carbon atoms can be readily and satisfactorily carried out by irradiating a liquid mixture of the anhydride, the desired hydrocarbon and a lower dialkyl ketone provided that for each mol of maleic anhydride at least, and preferably more than, two mols of the lower dialkyl ketone is present in the reaction mixture. Other reaction conditions include temperatures and pressures sufiicient to maintain the liquid reaction mixture. The temperature should be reasonably less than the pyrolysis temperatures of the reactants, i.e., about 5 to C. less. Under the above conditions, maleic anhydride adducts to benzene and mono-substituted benzenes at a good rate and in high yield thereby producing tricycle-compounds of the ice in which R is hydrogen or a saturated hydrocarbon radical as noted above. In general these reaction products are colorless, odorless crystalline materials.

By a lower dialkyl ketone is meant ketones of the formula RCOR in which R is an alkyl group containing fewer than 7 carbon atoms and can be the same or different.

In a preferred embodiment of the present process a solution of maleic anhydride, ethylbenzene and acetone in a weight ratio, respectively, of 10, 47 and 43 is irradiated with actinic light, for example by a mercury arc lamp. After about an ll-hour reaction period under ambient temperature and pressure conditions about 83 percent of the anhydride is found to have reacted. The acetone remaining in the reaction product mixture is removed by distillation leaving a solid, somewhat tacky, crystalline product. It is separated from the excess ethylbenzene by filtration and the collected solid washed several times with dry ethyl ether. For most purposes it is sufiiciently pure for use without further purification.

Variations in temperature and pressure in the present process have little, if any, effect upon the reaction rate. Therefore, it is most conveniently carried out under ambient conditions of temperature and pressure. The product is more soluble in the reaction mixture, in general, at higher temperatures and thus where the use of elevated temperatures is desirable, a pressure at least sufficient to maintain the liquid reaction phase is required. In general a reaction temperature above 250 C. is undesirable.

Ordinary actinic light in general is useful for the initiation of the present adduction reaction. In particular, at least an appreciable amount, for example, at least 1% thereof, should be in the wave length range below about 4000 A. As the fraction of the light in the 2000-4000A. wavelength region is increased, the relative efliciency of this process is increased. Light from a mercury arc source, or the like, is therefore particularly effective. On the other hand, for reasons of cost, sunlight is a desirable source of the activating energy for this process; although, of course, when sunlight is used and because of relative intensity factors, the reaction times will be longer.

When at least two mols of lower dialkyl ketone per mol of maleic anhydride is present, some enhancement of the reaction is experienced. In general, however, for a satisfactory rate and degree of conversion, at least 4 mols of acetone should be present. Preferred relative amounts are in the range from about 5-20 to 1, respectively. Larger ratios can be used and in some circumstances may be desirable except that in general at these higher ratios, the resulting dilution of the reactants may adversely affect the relative rate of the reaction in the usual sense.

In the course of the present reaction, 2 molecules of maleic anhydride add to one molecule of the aryl hydrocarbon. Stoichiometrically, a 2 to 1 mol ratio, respectively, is indicated. In general, however, an excess of the hydrocarbon relative to the anhydride is desirable. The addition of the second molecule of anhydride to the hydrocarbon appears to be so much faster than that of the first adduction that the mono-adduct is not detectable by ordinary means in the product mixture. The excess hydrocarbon therefore is useful for the maintenance of the required liquid reaction system in general. As in the case of the added dialkyl ketone, if the amount of the hydrocarbon becomes too excessive, dilution factors detract from the utility of the system. Relative ratios of aryl hydrocarbon to maleic anhydride in the range 0.1- 20 to 1, respectively, are in general satisfactory.

Lower alkyl ketones in general are useful in this process. Acetone is preferred for reasons of practicality. Other representative ketones useful in the process are 2- pentanone, 2- butanone, 6-methyl-3-heptanone, Z-methyl- 3-pentanone, 3-hexanone and the like dialkyl ketones.

Among the hydrocarbons contemplated for use in this is benzene and such representative hydrocarbons as toluene, t-butylbenzene, 2-phenylhexane, l-phenyl-S-t-butylhendecane, cyclododecylbenzene, 4-phenylhexadecane, 1- phenyleicosane, cyclohexylbenzene, C polypropylbenzene, cyclooctylbenzene, ethylbenzene, cumene, s-butylbenzene, l-phenyl-dodecane, Z-phenyI-heptane, 3-phenyldecane and the like mono-substituted benzene hydrocarbons in which the substituent group is a saturated hydrocarbon radical. Alkylbenzenes having fewer than 21 carbon atoms per alkyl group are preferred.

The C inclusive, mono-alkylbenzenes are particularly useful and desirable because the resulting tricyclo-9- C alkyl-dec-9-ene tetracarboxylic acid anhydrides ap pear to have only moderately elevated melting points. They lend themselves reasonably conveniently to the production of polyimide polymers and the like.

The following examples illustrate the invention.

EXAMPLES 1-3 Solutions of ethylbenzene and maleic anhydride or the foregoing plus acetone were placed in a quartz reaction vessel and irradiated with a 450-watt Hanovia mercury arc (2000-4000 A.) lamp. A large excess of ethylbenzene was present in each run. In these runs tricyc1o[4.2.0 ]-9- ethyl-doc 9 ene-3,4,7,8-tetracarboxylic acid dianhydride was formed. The extent of the reaction at various times was determined by vapor phase chromatographic analysis of aliquots of the reaction mixture as listed in Table I.

TAB LE I 1 Percent MA reacted M01 ratio acetonezMA 4 hrs. 8 hrs. 11 hrs.

I Maleic anhydride. b 63% yield of desired tricyclo-product recovered.

The above runs demonstrate that the presence of a substantial molar excess of a lower dialkyl ketone over maleic anhydride in a maleic anhydride-alkylbenzene photolytic adduction reaction mixture markedly improves rates and conversions therein.

EXAMPLE 4 EXAMPLES 5-10 In experiments analogous to the above examples and using acetone promoter, the dianhydride maleic adducts were prepared in good yields from benzene, toluene, cumene, t-buylbenzene, C -C cracked wax olefin benzene y i. and G -C straight chain alkylbenzene.

4 The tricyclo-decene dianhydrides obtained from the above alkylbenzenes were characterized by determination of equivalent weights of the dianhydrides, of their tetra- .carboxylic acid hydrolysis products, and of the carbon and hydrogen contents for the methyl ester derivatives. All of the experimental values approximated within acceptable limits the theoretical values. The infrared spectra of the dianhydrides obtained from the alkylbenzenes were the same in all the essential details, except, of course, for differences in the 1400-1500 cm? region which correspond to differences in the alkyl group. A representative spectra (figure) for the cumene adduct is attached. Finally, the nuclear magnetic resonance spectra of the tetramethyl ester derivatives of the dianhydrides established that they contain but a single vinyl proton (86.2). Thus the alkyl substituent group is in the vinyl position Polyimides from 9-alkyl-tricyclodecene-9 dianhydrides The alkyl substituted dianhydrides of this process are useful for the production of tough high melting polyimides. While the dianhydride obtained from benzene has an extremely high melting point and is thus somewhat difficult to use in a polymerization, the alkyl substituted analogues have substantially lower melting points (Table H) and thus can be used in a polymerization in conjunction with a suitable diamine to produce imide polymers.

The lower polymethylene diamines, i.e., the C -C inclusive, methylenedi-amines are particularly suitable as shown by the following example.

EXAMPLE 11 Hexamethylene diamine was reacted with the cumene maleic anhydride adduct, i.e., tricyclo-9-i-propyl-decene- 9,3,4,7,8 tetracarboxylic acid dianhydride. Equimolar amounts were employed. The diamine was dissolved in N,N-dimethyl acetamide and the dianhydride was then added slowly to the solution. During the addition the solution was efficiently stirred. The solution viscosity increased, and at the completion of the addition, the resulting light brown colored solution was poured into a flat aluminum dish. The solvent was removed by heating the dish and its contents in a vacuum oven at 70 C. and a pressure of 20 mm. of Hg. The temperature was then increased to C. and maintained for about 4 hours. The cured polyimide film (0.12 mm. thick) had a melting point of 450 C.; a molecular weight of about 300,000; a tensile strength of 1083 pounds; and an initial modulus of 20.83 10 with a 25 percent elongation at the breakin g point.

The above example demonstrates that useful substantially linear high melting methylene bridged polyimide polymers can be prepared from the direct reaction of the alkylbenzene-maleic anhydride adducts of the present process with the lower polymethylene diamines. These polymers appear to be readily prepared in the 10 -10 molecular weight unit range.

WAVELENGTH (MICRONS) 7' 8 9 10 ssogam ce Infrared Spectrum (KBr) of the Cumene-Maleic Anhydride Photoadduct The high melting tricyclo-decene dianhydrides produced in the present process are useful for the preparation of extremely tough high melting polyimides in their reactions with aryl diamines. These polymers are useful as coating materials and for their heat and radiation resistance.

EXAMPLE 12 To an efiicient-ly stirred mixture of grams (0.025 mol) of 4,4'-diaminodiphenyl ether in 90 g. of N,N-dimethyl acetamide was slowly added 7.6 g. (0.025 mol) of tricyclo-[4.2.0 -9-ethyl-dec-9 ene 3,4,7,8-tetracarboxylic acid anhydride. During the addition a noticeable rise in viscosity occurred. The resulting light brown solution was poured into a flat dish and the acetamide removed by evaporation in a vacuum oven maintained at about 70 C. and mm. of Hg pressure. The temperature was then raised and mantained at about 140 C. for 4 hours. The resulting polyimide had a melting point in excess of 600 C. and a molecular weight of about 300,000.

The above examples demonstrate that a diahydride 0f the formula in which R can be hydrogen or an alkyl group having fewer than 5 carbon atoms is useful in its reaction at elevated temperatures and reduced pressures with aryl diamines such as 4,4-diaminophenyl ether, p-xylylene diamine, m-xylylene diamine, and 4,4-diaminodiphenyl for the production of polyimides having a molecular weight of at least about 300,000 units.

As will be evident to those skilled in the art, numerous modifications in this process can be made or followed, having in mind the foregoing disclosure and discussion without departing from the spirit or scope of the disclosure or from the scope of the claims.

What is claimed is:

1. The solid polyimide obtained from the pyropolymerization of a carboxylic dianhydride and a diamine wherein the anhydride is of the formula in which R is an alkyl group having a carbon atom content in the range from 7 to 20, inclusive, and wherein the diamine is a C inclusive, polymethylene diamine, said polymerization being eflected by:

(1) forming a mixture of the anhydride and amine in about a l to 1 molar ratio in a solvent and then evaporating the solvent under reduced pressure at about 70 C.; and

(2) heating the product of (1) to a temperature of about C.

2. The solid polyimide of claim 1 wherein said diamine is hexamethylene diamine.

3. The solid polyimide obtained from the pyropolymerization of a carboxylic dianhydride and a diamine Wherein the anhydride is of the formula 8 in which R is an alkyl group having a carbon atom con- References Cited tent in the range below about 21, and wherein the diamine UNITED STATES PATENTS '1',1thld",'1- gig igg gg j j i gggfi y lamme sald PO ym 3,037,966 6/1962 Chow et a1 26078 (1) forming a mixture of the anhydride and amine in 5 ggg 6/1926 g gg 2% 'g about a 1 to 1 molar ratio in a solvent and then 42 1/19 8 m s aw evaporating the solvent under reduced pressure at about 70 C; and HAROLD D. ANDERSON, Primary Examiner (2) heating the product of (1) to a temperature of aFout CL 0 C 10 117-161 P; 26032.6 N, 47 CP 

